How Fast Does a 40cc Dirt Bike Go?

While dirt bikes have different engine capacities, at the base is 40cc. This mini dirt bike is always the go-for choice for kids. But how fast does a 40cc dirt bike go?

40cc dirt bikes can go at a maximum speed of 15-22mph under favorable riding conditions. That includes a smoother terrain, good weather, automatic transmission, and rider’s confidence.

Overall, 40cc dirt bikes cannot match the speed of big-size engines. But given that 40cc dirt bikes target kids, 15-22mph is safe enough for these adventurous youngsters. In most cases, the young bikers don’t go past 15mph.

This 40cc review will focus on the dirt bike’s speed and other essential aspects such as preferred rider’s age, weight, load capacity, fuel capacity, mileage, and cost.

We’ll also compare the speed of 40ccc dirt bikes with that of other dirt bikes.

How Fast Does A 40cc Dirt Bike Go in MPH?

Generally, most 40cc manufacturers suggest that 40cc dirt bikes can hit 15-22mph, a comfortable speed for kids. But for the rider to realize such a height, the conditions have to be favorable, which include the following:

Smoother Terrain – 40cc dirt bikes generally go faster when the trails are smoother. Issues like portholes and rough patches slow the dirt bikes down.
Good Weather – Expect 40cc dirt bikes like other dirt bikes to go faster when the weather is good. Factors like snow, rain, strong wind, and excess heat forces your young rider to go slower as they are pretty uncomfortable.
Automatic Transmission – Kids are not like adults; they need some help to reach top speed, and that’s where an automatic transmission system comes in. Generally, an automatic transmission system saves the rider’s energy, making it easy to ride fast and hit top speed.
Rider’s Confidence – Your young rider can only reach top speed if confident riding fast. Remember, some kids are more confident than others, and the more comfortable they are riding fast, the likelier they are to hit top speed. So, it all depends on the kid’s confidence level.

In addition to the above conditions, it’s worth mentioning that factors like bike weight and engine stroke have a role to play. The lighter the dirt bike, the likelier it is to go fast.

And when it comes to the engine stroke, 40cc dirt bikes usually come with a 4-stroke engine, which is not the lightest but is more stable. As a result, it’s safer for kids as they won’t ride too fast

How Fast Does a 40cc Dirt Bike Compare with Other Bikes?

Overall, since 40cc dirt bikes have the smallest engines, you can expect them to be the slowest. So, the bigger the engine size, the slower the dirt bike. Even better, the engine size is directly proportional to the dirt bike’s strength.

In that case, expect big-size engines to not only go faster but also bear huge loads.

Here’s a table showing how fast 40cc compares to the potential top speed of other dirt bikes.

Engine Size	Potential Top Speed
40cc	15-22mph
50cc	25-40mph
70cc	45mph
85cc	50mph
100cc	55mph
125cc	60mph
150cc	60mph
250cc	85mph
450cc	90mph
650cc	100mph
1000cc	100mph plus

40CC Dirt Bike Reviewed

Getting the right 40cc dirt bike is essential, but you must understand a few basics to realize that. They include:

Preferred Rider’s Age

All 40cc dirt bikes come with the manufacturer’s recommended age. While most manufacturers recommend at least eight years, some insist on 13 years and above. So, it’s essential to confirm this critical detail.

Weight and Load Capacity

Most 40cc dirt bikes weigh 53-60 pounds but can bear 160-165 pounds. That means some of them can hold an adult’s weight as long as the adult doesn’t exceed the weight limit.

However, I insist that you confirm the load capacity first before getting a 40cc dirt bike. That will ensure it bears your weight well.

Fuel Capacity and Mileage

The average 40cc dirt bike comes with a 0.32-gallon gas tank which is enough to last you 27 miles. Others come with a 1.8-liter capacity (equivalent to 0.48 gallons) to last you much longer. So, if you want extra mileage, you have to go for a larger gas tank.

40cc Dirt Bike Cost

Different 40cc dirt bikes come at different prices, depending on the brand. But overall, most of them cost slightly under $500. So, they are generally affordable and decent alternatives to kids’ bicycles.

40cc Dirt Bike Brands

Not all dirt bike manufacturers make 40cc options. A majority of them concentrate on large-capacity engines.

From research, here are the three leading 40cc brands:

1. X-Pro

X-Pro makes some of the fastest and most reliable 40cc dirt bikes. Their 4-stroke dirt bikes are stable, thus safer for young kids than 2-stroke, quicker but less stable.

X-Pro 40cc dirt bikes not only enjoy quick acceleration but are also relatively smoother and steadier. They also enjoy a good suspension and braking system.

Moreover, they are EPA-approved, thus safer for your young rider.

Here are the fastest X-Pro dirt bikes on Amazon, all capable of hitting 22mph:

2. Fit Right Products (FRP)

FRP is another leading dirt bike brand that promises fast, safe, and reliable dirt bikes for your youngster. Its 40cc dirt bikes also come with 4-stroke engines, and they are EPA-approved.

FRP dirt bikes are usually more robust, holding up to 165 pounds while maintaining good top speed.

One such dirt bike is the FRP DB003 (View on Amazon), which can hold up to 160 pounds while maintaining a maximum top speed of 18mph.

3. XtremepowerUS

XtremepowerUS is popularly known for making high-capacity EPA-approved dirt bike engines. But still, the manufacturer makes 40cc dirt bikes which promise the same quality as the high-capacity options.

Expectedly, their 40cc dirt bikes are 4-stroke, thus more stable and safer. They mostly come with steel frames to bear massive loads.

Two excellent choices on Amazon which can hold up to 165 pounds while enjoying a top speed of 18mph are:

Can You Make Your 40cc Dirt Bike Faster?

40cc dirt bikes, like every other dirt bike, can go faster with a few adjustments. So, if you are looking to get to 22mph or surpass it, these adjustments are a must-consider:

Upgrade the bike’s gas – There’s a vast difference between using ethanol-based gas and high-octane fuel. The latter makes your dirt bike faster than the former, thus worth upgrading.
Add a few comforts – In particular, add a cushioned seat cover, footpegs, and grips to the dirt bike to make it more comfortable. If the dirt bike is comfortable, it’ll be easy to ride faster.
Correct tire pressure – Using the correct tire pressure helps a long way in making a dirt bike speedier.
Upgrade its exhaust – getting a better exhaust makes the engine more breathable, boosting the dirt bike’s speed.
Change the air filters – Dirt and other clogs make the air filters less effective and the engine less breathable. So, consider replacing them often to improve the engine’s breathability and efficiency.

Can Adults Ride 40cc Dirt Bikes?

Ordinarily, 40cc dirt bikes are mini bikes which means they are best for kids. However, some options have a taller seat height and can bear up to 165 pounds.

In that case, they can bear the weight of adults who don’t weigh more than 165 pounds. One perfect example is the XtremepowerUS Pro-Edition Mini Dirt Bike (View on Amazon)

How to Choose the Best 40cc Dirt Bike

Here are essential considerations for getting a decent 40cc dirt bike:

Load Capacity – The dirt bike must bear your child’s weight. In that case, you’ve to keenly consider its load/carry capacity. Note that most 40cc dirt bikes come with a 160-165-pound capacity, but you’ve to confirm that.
Engine Stroke – Usually, 40cc dirt bikes come as 4-stroke. 4-stroke engines have lower emissions and are more stable at high speed, thus safer for kids. So, that makes sense!
Build Quality – You want a dirt bike that can take on all the off-road abuse. So, everything from the frame and handles to the engine should be solid enough.
Seat Height – Just because the dirt bike can hold your weight doesn’t mean it will fit. You also have to consider its seat height to ensure you’ll sit comfortably.